Graduation Year

2006

Document Type

Thesis

Degree

M.S.E.V.

Degree Granting Department

Environmental Engineering

Major Professor

Robert P. Carnahan, Ph.D.

Committee Member

Audrey D. Levine, Ph.D.

Committee Member

Paul Zandbergen, Ph.D.

Keywords

asset, utility, IMS, IMMS, main, rehabilitation, hydraulic, model

Abstract

Maintenance, repair, and replacement of transmission mains and distribution system piping is expected to cost approximately $75 billion over the next two decades to ensure that public water systems are capable of providing the United States with safe drinking water. However, there is a significant gap between the funds available and the projected costs of infrastructure replacement or rehabilitation. Infrastructure Management Systems (IMS) have been developed to assist utilities and decision-makers in determining how to allocate resources for infrastructure. This project utilizes theTampa Water Department (TWD) as a case study to develop a tool for prioritizing infrastructure replacement.

TWD is responsible for managing over 2,240 miles of pipeline. Building booms in the 1920s and 1950s have inadvertently resulted in a significant need to replace or rehabilitate pipelines due to the aging of the overall water supply infrastructure. To address this problem, TWD is taking the first steps in applying IMS to transmission anddistribution pipelines. Currently, approximately 500 miles of water mains have been slated for replacement or rehabilitation. The TWD has a GIS that has been used to map and integrate information on main breaks, service line breaks, customer complaints and modeled water age. Information on fire hydrant spacing and line flushing dates are also integrated into the GIS.

Following development of the GIS based infrastructure replacement prioritization system, approximately 3,000 pipe segments were identified and queries were performed to help develop cost to benefit analyses. The results were used to develop a prioritized list of potential capital projects and incorporate the time value of money and event forecasting. The GIS was also used to develop indicators of the overall infrastructure condition. From this analysis it was possible to develop an approach to categorize projects and identify the resources needed to address high priority problems associated with undersized mains, unlined cast iron mains, asbestos cement mains, and hydraulic looping projects.

As water infrastructure rehabilitation and replacement needs increase in the future, the need for adaptable methods to prioritize capital spending will also increase.This study has demonstrated the ability to prioritize long-term and short-term infrastructure projects using a GIS platform in conjunction with databases and spreadsheets.

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